Kling 4.0 generates videos from text prompts and image or video references at 720p or 1080p, with durations from 3 to 30 seconds and per-shot prompts. Kling 4.0 is available in the playground and fal Agent. API access is coming soon.

kling/v4/reference-to-video

Inference

Commercial use

Partner

Schema

LLMs

Playground API

kling/v4/reference-to-video

Schema

kling/v4/reference-to-video

Inference

Commercial use

Partner

Schema

LLMs

Playground API

1. Calling the API

2. Authentication

API Key

3. Queue

4. Files

5. Schema

About

Generate videos with Kling 4.0 Reference to Video

1. Calling the API#

Install the client#

The client provides a convenient way to interact with the model API.

npm install --save @fal-ai/client

Migrate to @fal-ai/client

The @fal-ai/serverless-client package has been deprecated in favor of @fal-ai/client. Install the new package and update your imports — see client setup.

Setup your API Key#

Set FAL_KEY as an environment variable in your runtime.

export FAL_KEY="YOUR_API_KEY"

Submit a request#

The client API handles the API submit protocol. It will handle the request status updates and return the result when the request is completed.

import { fal } from "@fal-ai/client";

const result = await fal.subscribe("kling/v4/reference-to-video", {
  input: {},
  logs: true,
  onQueueUpdate: (update) => {
    if (update.status === "IN_PROGRESS") {
      update.logs.map((log) => log.message).forEach(console.log);
    }
  },
});
console.log(result.data);
console.log(result.requestId);

2. Authentication#

The API uses an API Key for authentication. It is recommended you set the FAL_KEY environment variable in your runtime when possible.

API Key#

In an environment where you cannot set environment variables, you can configure the API key manually on the client.

import { fal } from "@fal-ai/client";

fal.config({
  credentials: "YOUR_FAL_KEY"
});

Protect your API Key

When running code on the client-side (e.g. in a browser, mobile app or GUI applications), make sure to not expose your FAL_KEY. Instead, use a server-side proxy to make requests to the API. For more information, check out our server-side integration guide.

3. Queue#

Long-running requests

For long-running requests, such as training jobs or models with slower inference times, it is recommended to check the Queue status and rely on Webhooks instead of blocking while waiting for the result.

Submit a request#

The client API provides a convenient way to submit requests to the model.

import { fal } from "@fal-ai/client";

const { request_id } = await fal.queue.submit("kling/v4/reference-to-video", {
  input: {},
  webhookUrl: "https://optional.webhook.url/for/results",
});

Fetch request status#

You can fetch the status of a request to check if it is completed or still in progress.

import { fal } from "@fal-ai/client";

const status = await fal.queue.status("kling/v4/reference-to-video", {
  requestId: "764cabcf-b745-4b3e-ae38-1200304cf45b",
  logs: true,
});

Get the result#

Once the request is completed, you can fetch the result. See the Output Schema for the expected result format.

import { fal } from "@fal-ai/client";

const result = await fal.queue.result("kling/v4/reference-to-video", {
  requestId: "764cabcf-b745-4b3e-ae38-1200304cf45b"
});
console.log(result.data);
console.log(result.requestId);

4. Files#

Some attributes in the API accept file URLs as input. Whenever that's the case you can pass your own URL or a Base64 data URI.

Data URI (base64)#

You can pass a Base64 data URI as a file input. The API will handle the file decoding for you. Keep in mind that for large files, this alternative although convenient can impact the request performance.

Hosted files (URL)#

You can also pass your own URLs as long as they are publicly accessible. Be aware that some hosts might block cross-site requests, rate-limit, or consider the request as a bot.

Uploading files#

We provide a convenient file storage that allows you to upload files and use them in your requests. You can upload files using the client API and use the returned URL in your requests.

import { fal } from "@fal-ai/client";

const file = new File(["Hello, World!"], "hello.txt", { type: "text/plain" });
const url = await fal.storage.upload(file);

Auto uploads

The client will auto-upload the file for you if you pass a binary object (e.g. File, Data).

Read more about file handling in our file upload guide.

5. Schema#

Input#

prompt string

Text prompt. Reference inputs as @Image1, @Video1, @Element1, etc. Either prompt or multi_prompt must be provided.

multi_prompt list<KlingV4Shot>

Per-shot prompts for multi-shot generation. The video duration is the sum of the shot durations.

duration integer

Video duration in seconds (3-30). Default value: 5

start_image_url string

Optional image to use as the first frame. Counts toward the image reference limit.

image_urls list<string>

Reference images, referenced as @Image1, @Image2, ... (max 10).

video_urls list<string>

Reference videos (3-30s each, 30s combined with element videos), referenced as @Video1, @Video2, ... (max 5).

elements list<KlingV4Element>

Characters/objects, referenced as @Element1, @Element2, ... (max 7). Up to 3 elements may carry a voice_id and up to 3 may be video elements.

resolution ResolutionEnum

Output resolution. Default value: "1080p"

Possible enum values: 720p, 1080p

aspect_ratio AspectRatioEnum

Aspect ratio of the generated video. 'auto' adapts it to the references. Default value: "16:9"

Possible enum values: auto, 16:9, 9:16, 1:1, 21:9

{
  "prompt": "@Element1 and @Element2 are having dinner at the table in @Image1",
  "multi_prompt": null,
  "duration": 5,
  "image_urls": null,
  "video_urls": null,
  "elements": null,
  "resolution": "1080p",
  "aspect_ratio": "16:9"
}

Output#

video File* required

The generated video.

{
  "video": {
    "content_type": "video/mp4",
    "file_name": "output.mp4",
    "file_size": 3020124,
    "url": "https://v3b.fal.media/files/b/0aac4497/-fHk6MiMZhLy2FncCbyM7_clip_reference.mp4"
  }
}

Other types#

File#

url string* required

The URL where the file can be downloaded from.

content_type string

The mime type of the file.

file_name string

The name of the file. It will be auto-generated if not provided.

file_size integer

The size of the file in bytes.

KlingV4Shot#

prompt string* required

The prompt for this shot.

duration integer

Shot duration in seconds. Default value: 5

KlingV4Element#

frontal_image_url string

The frontal image of the element (main view).

reference_image_urls list<string>

Additional views of the element from different angles (1-3).

video_url string

A video of the element, used instead of images (3-30s).

voice_id string

Voice bound to this element. Create one with https://fal.ai/models/fal-ai/kling-video/create-voice

Related Models

1. Calling the API

2. Authentication

API Key

3. Queue

4. Files

5. Schema

About

Generate videos with Kling 4.0 Reference to Video

1. Calling the API#

Install the client#

The client provides a convenient way to interact with the model API.

npm install --save @fal-ai/client

Migrate to @fal-ai/client

The @fal-ai/serverless-client package has been deprecated in favor of @fal-ai/client. Install the new package and update your imports — see client setup.

Setup your API Key#

Set FAL_KEY as an environment variable in your runtime.

export FAL_KEY="YOUR_API_KEY"

Submit a request#

The client API handles the API submit protocol. It will handle the request status updates and return the result when the request is completed.

import { fal } from "@fal-ai/client";

const result = await fal.subscribe("kling/v4/reference-to-video", {
  input: {},
  logs: true,
  onQueueUpdate: (update) => {
    if (update.status === "IN_PROGRESS") {
      update.logs.map((log) => log.message).forEach(console.log);
    }
  },
});
console.log(result.data);
console.log(result.requestId);

2. Authentication#

The API uses an API Key for authentication. It is recommended you set the FAL_KEY environment variable in your runtime when possible.

API Key#

In an environment where you cannot set environment variables, you can configure the API key manually on the client.

import { fal } from "@fal-ai/client";

fal.config({
  credentials: "YOUR_FAL_KEY"
});

Protect your API Key

3. Queue#

Long-running requests

Submit a request#

The client API provides a convenient way to submit requests to the model.

import { fal } from "@fal-ai/client";

const { request_id } = await fal.queue.submit("kling/v4/reference-to-video", {
  input: {},
  webhookUrl: "https://optional.webhook.url/for/results",
});

Fetch request status#

You can fetch the status of a request to check if it is completed or still in progress.

import { fal } from "@fal-ai/client";

const status = await fal.queue.status("kling/v4/reference-to-video", {
  requestId: "764cabcf-b745-4b3e-ae38-1200304cf45b",
  logs: true,
});

Get the result#

Once the request is completed, you can fetch the result. See the Output Schema for the expected result format.

import { fal } from "@fal-ai/client";

const result = await fal.queue.result("kling/v4/reference-to-video", {
  requestId: "764cabcf-b745-4b3e-ae38-1200304cf45b"
});
console.log(result.data);
console.log(result.requestId);

4. Files#

Some attributes in the API accept file URLs as input. Whenever that's the case you can pass your own URL or a Base64 data URI.

Data URI (base64)#

Hosted files (URL)#

You can also pass your own URLs as long as they are publicly accessible. Be aware that some hosts might block cross-site requests, rate-limit, or consider the request as a bot.

Uploading files#

We provide a convenient file storage that allows you to upload files and use them in your requests. You can upload files using the client API and use the returned URL in your requests.

import { fal } from "@fal-ai/client";

const file = new File(["Hello, World!"], "hello.txt", { type: "text/plain" });
const url = await fal.storage.upload(file);

Auto uploads

The client will auto-upload the file for you if you pass a binary object (e.g. File, Data).

Read more about file handling in our file upload guide.

5. Schema#

Input#

prompt string

Text prompt. Reference inputs as @Image1, @Video1, @Element1, etc. Either prompt or multi_prompt must be provided.

multi_prompt list<KlingV4Shot>

Per-shot prompts for multi-shot generation. The video duration is the sum of the shot durations.

duration integer

Video duration in seconds (3-30). Default value: 5

start_image_url string

Optional image to use as the first frame. Counts toward the image reference limit.

image_urls list<string>

Reference images, referenced as @Image1, @Image2, ... (max 10).

video_urls list<string>

Reference videos (3-30s each, 30s combined with element videos), referenced as @Video1, @Video2, ... (max 5).

elements list<KlingV4Element>

Characters/objects, referenced as @Element1, @Element2, ... (max 7). Up to 3 elements may carry a voice_id and up to 3 may be video elements.

resolution ResolutionEnum

Output resolution. Default value: "1080p"

Possible enum values: 720p, 1080p

aspect_ratio AspectRatioEnum

Aspect ratio of the generated video. 'auto' adapts it to the references. Default value: "16:9"

Possible enum values: auto, 16:9, 9:16, 1:1, 21:9

{
  "prompt": "@Element1 and @Element2 are having dinner at the table in @Image1",
  "multi_prompt": null,
  "duration": 5,
  "image_urls": null,
  "video_urls": null,
  "elements": null,
  "resolution": "1080p",
  "aspect_ratio": "16:9"
}

Output#

video File* required

The generated video.

{
  "video": {
    "content_type": "video/mp4",
    "file_name": "output.mp4",
    "file_size": 3020124,
    "url": "https://v3b.fal.media/files/b/0aac4497/-fHk6MiMZhLy2FncCbyM7_clip_reference.mp4"
  }
}

Other types#

File#

url string* required

The URL where the file can be downloaded from.

content_type string

The mime type of the file.

file_name string

The name of the file. It will be auto-generated if not provided.

file_size integer

The size of the file in bytes.

KlingV4Shot#

prompt string* required

The prompt for this shot.

duration integer

Shot duration in seconds. Default value: 5

KlingV4Element#

frontal_image_url string

The frontal image of the element (main view).

reference_image_urls list<string>

Additional views of the element from different angles (1-3).

video_url string

A video of the element, used instead of images (3-30s).

voice_id string

Voice bound to this element. Create one with https://fal.ai/models/fal-ai/kling-video/create-voice

kling/v4/reference-to-video

Table of contents

Table of contents

kling/v4/reference-to-video

Table of contents

1. Calling the API

2. Authentication

3. Queue

4. Files

5. Schema

About

1. Calling the API#

Install the client#

Migrate to @fal-ai/client

Setup your API Key#

Submit a request#

2. Authentication#

API Key#

Protect your API Key

3. Queue#

Long-running requests

Submit a request#

Fetch request status#

Get the result#

4. Files#

Data URI (base64)#

Hosted files (URL)#

Uploading files#

Auto uploads

5. Schema#

Input#

Output#

Other types#

File#

KlingV4Shot#

KlingV4Element#

Related Models

Table of contents

Table of contents

1. Calling the API

2. Authentication

3. Queue

4. Files

5. Schema

About

1. Calling the API#

Install the client#

Migrate to @fal-ai/client

Setup your API Key#

Submit a request#

2. Authentication#

API Key#

Protect your API Key

3. Queue#

Long-running requests

Submit a request#

Fetch request status#

Get the result#

4. Files#

Data URI (base64)#

Hosted files (URL)#

Uploading files#

Auto uploads

5. Schema#

Input#

Output#

Other types#

File#

KlingV4Shot#

KlingV4Element#

Related Models